Arachidic Acid Langmuir-Blodgett Films Research Articles

Effects of Cu(II) on the Formation and Orientation of an Arachidic Acid Langmuir-Blodgett Film.

The influence of the copper(II) ion on the formation, morphology, and organization of an arachidic acid monolayer was investigated using Langmuir-Blodgett (LB) monolayers, Π-A isotherms, and Brewster angle microscopy (BAM). Our findings indicate that a Cu2+-complexed LB film exhibits an order that depends on the subphase pH, analogous to other metal ions. Yazdanian , M. ; et al. Ionic Interactions of Fatty Acid Monolayers at the Air-Water Interface . Langmuir 1990 , 6 , 1093 - 1098 . Kurnaz , M. L. ; et al. Morphology of Microphase Separation in Arachidic Acid-Cadmium Arachidate Langmuir-Blodgett Multilayers . J. Phys. Chem. 1996 , 100 , 11113 - 11119 . The metal ion facilitates the formation of solid-phase films at surface pressures as low as 5 mN/m. The films exhibit a rigid, ordered phase, evidenced by the absence of a collapse point and an increase in surface pressure rather than the typical sharp decrease in surface pressure, indicative of film failure. Amphiphile ionic charge vs pH (i.e., the extent of arachidic acid protonation) plays a role in the observed absence of collapse and the ability of the films to maintain order and cohesion at high surface pressures (ca. 65 mN/m). Additionally, film thickness data suggest that the incorporation of Cu2+ ions induces a change in orientation of the aliphatic chains of the amphiphiles and that amphiphile solubility in the subphase may play a role in the observed film behavior at low surface areas and high pH.

J-Aggregation Characteristics of Merocyanine Dye with Arachidic Acid LB Films by Heat Treatment

For a measurement of J-aggregation characteristics by heat treatment, we fabricated arachidic acid (AA)-Merocyanine dye mixed Langmuir-Blodgett (LB) films. pi-A curves were used to investigate the surface pressure of the LB film from a liquid to a solid state while the pressure ranged from 35 and 40 mN/m. When the surface pressure reached 40 mN/m, a monolayer was deposited onto the hydrophilic glass substrates by Y-type deposition. For the UV spectrum observation, a multi layer film was deposited. A narrowing of the red-shifted band was observed. We studied the effect of heat treatments at temperatures below 60 degrees C by observing the UV spectra of merocyanine dye (MD). The J-aggregation was centered at 550-590 nm at 20 degrees C-25 degrees C. We will study the system before and after the application of heat treatment J-aggregation. The J-aggregation will be thermally induced in the mixed LB films by heat treatments at various temperatures. We expect that after heat treatment, the spectral shape and peak of the band will be altered. We investigated that morphology of MD using STM. Also I-V curve was decreased as increasing temperatures.

Tetrapyrazinoindoloporphyrazine Langmuir-Blodgett films

We fabricated tetra(5-n-nonyl-8-tert-butyl-2,3-pyrazino[2,3-b]indolo)porphyrazinato copper(II) (Cu-Pc-C8) Langmuir-Blodgett (LB) films. We further investigated the influence of arachidic acid (AA) as a transfer promoter, as well as the effect of dipping speed, on the deposition of the films on hydrophilic and hydrophobic substrates. In the case of pure Cu-Pc-C8 LB deposition on a hydrophilic substrate, the transfer ratio was close to one for up-stroke depositions, but the previously deposited film was peeled off and re-spread onto water at down-stroke depositions. Whereas the stability of the Cu-Pc-C8 LB films was not improved by AA addition on hydrophilic substrates, the deposition of Cu-Pc-C8 was significantly improved by the presence of AA on a hydrophobic substrate. The AA-assisted deposition had transfer ratio of close to 1 and was essentially stable up to 10-layer depositions. Comparison of the UV-visible spectrum of a Cu-Pc-C8/AA LB film with that of Cu-Pc-C8/AA solution in dichloroethane revealed that the Soret and Q bands for the Cu-Pc-C8/AA LB film were broadened and red-shifted due to the aggregation of phthalocyanines upon assembly in the LB film.

CdS/ZnS core–shell nanoparticles in arachidic acid LB films

Core–shell CdS/ZnS nanoparticles in arachidic acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H 2S gas followed by intercalation of Zn 2+ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.

1114 ナノ薄膜の表面エネルギーに関する研究 : アラキジン酸LB膜を用いた有効分散成分理論の検証(マイクロトライボロジー,一般講演)

Dependences of surface energy on ultrathin solid film thickness were investigated experimentally and theoretically. The arachidic acid Langmuir-Blodgett film on a glass plate was used as an ultrathin film sample. The surface energies as a function of the LB film thickness were experimentally obtained from contact angle measurements. The theoretical equation of the dispersive component of the surface energy of the ultrathin film were derived from the van der Waals pressure equation for a multilayered system. The theoretical values were found to agree with the experimental ones and the theoretical equation presented in this study were considered to be useful for prediction of the surface energy of the ultrathin film on a solid substrate.

Electrical characterisation of poly(methyl methacrylate)/arachidic acid Langmuir–Blodgett films

A series of poly(methyl methacrylate) (PMMA) molecules with different molecular weights and arachidic acid has been used to fabricate alternate layer Langmuir–Blodgett (LB) films onto aluminum coated glass substrates and electrical properties of these LB films have been investigated. The area per molecule for PMMA molecules was found to be approximately 2000 nm 2. I–V measurements showed that there is a polarity in the alternate layer LB films. Schottky barrier height values have been calculated using alternate layer type (AL-type) LB films.

Thermodynamic and Spectroscopic Studies on the Nickel Arachidate−RNA Polymerase Langmuir−Blodgett Monolayer

The Langmuir-Blodgett (LB) monolayers offer a unique system to study molecular interaction at the air-water interface with reduced dimensionality. In order to develop this further to follow macromolecular interactions at equilibrium, we first characterized the Ni (II)-arachidate (NiA) monolayer at varying conditions. Subsequently, the interaction between NiA and histidine-tagged RNA polymerase (HisRNAP) were also studied. LB films of arachidic acid-NiA and NiA-RNAP with different mole fractions were fabricated systematically. Surface pressure versus area per molecule (P-A) isotherms were registered, and the excess Gibbs energy of mixing was calculated. The LB films were then deposited on solid supports for Fourier transform infrared (FTIR) spectroscopic measurements. The FTIR spectra revealed the change in the amount of incorporated Ni (II) ions into the arachidic acid monolayer with the change in pH and the increasing mole fraction of RNAP in the NiA monolayer with its increasing concentration in the subphase. The system developed here seems to be robust and can be utilized to follow macromolecular interactions.

Enhancement of ferroelectricity in Langmuir–Blodgett multilayer films of weak-polar organic molecules

Ferroelectricity in Langmuir–Blodgett (LB) films (Z-type and alternated Y-type) of nitrogencrown (NC) and arachidic acid (AA) was investigated by electric polarization measurements and small angle X-ray diffraction (SAXD). For Z-type AA LB multilayer and the AA LB films incorporating barium ions, as well as for Z-type NC LB multilayer and the Y-type NC/AA alternating LB films, hysteresis loops of the samples were observed and confirmed existence of the remnant polarizations in the LB films. Their corresponding remnant polarizations were found to be 15, 180, 450 and 9400 μC m −2, respectively. Therefore, the maximum ratios of remnant polarizations up to 620 (9400/15)-folds were obtained from NC/AA alternating LB films. The enhancement of ferroelectricity in NC/AA alternating LB films was observed for the first time. It was demonstrated that the enhancement of ferroelectricity in the LB films could be created by incorporation of barium ions into the LB film structures and strong interaction due to electron clouds redistribution largely originated from the compact insertion configuration of AA between two chains of NC molecules in interleaving films.

The role of liquid penetration in detergency of long‐chain fatty acid

AbstractThe detergency phenomena of a solid oily contaminant assessed with a quartz crystal microbalance (QCM) technique was discussed on the basis of surface energetics. Polyethylene, nylon 6, and cellulose acetate films were prepared on gold electrodes of the QCM by a spin‐coating method. Arachidic acid was deposited onto the QCM with and without polymer films by the Langmuir‐Blodgett (LB) technique. The QCM was then ultrasonically cleaned in aqueous solutions containing surfactant, ethanol, and alkali. The removal efficiency of the LB films of arachidic acid from the gold and polymer substrates was determined from the frequency change of the QCM due to cleaning. The efficiency was greatest for cellulose acetate, followed by nylon 6, gold, and polyethylene. For every substrate, the removal efficiency was found to increase with increasing surfactant or ethanol concentration. In the presence of sodium hydroxide, the removal efficiency further increased. The experimentally determined contact angles and surface free energies were influenced by surfactant and ethanol concentrations; however, they were not influenced by the addition of sodium hydroxide. This suggested the saponification of arachidic acid under alkali conditions was a major mechanism of fatty acid removal. The dependences of the kind of substrate and surfactant and ethanol concentrations on the removal efficiency were explained in terms of the free energy change resulting from penetration of the detergent solution between the arachidic acid film and the substrate in the zone of contact. Liquid penetration as well as saponification was found to be an oil removal mechanism in the present system.

Investigation of ITO surface modified by NPB and arachidic acid LB films

NPB and arachidic acid (AA) are introduced to the ITO surface through Langmuir–Blodgett (LB) technique to modify the hydrophilic surface to hydrophobic surface. The π– A isotherms and AFM images of NPB–arachidic acid with different mol concentration show that they can form stable and condensed LB films, and the compactness are increased with the increasing of the NPB molecular concentration. The surface morphologies of the composite films were investigated by atomic force microscopy (AFM). The surface properties of the film are characterized by contact angle and cyclic voltammetry.

Polyimide 터널 장벽을 이용한 Au/polyimide/유기 단분자막/Pb 구조에서 비탄성 전자 터널링에 관한 연구

Using polyimide Langmuir-Blodgett(LB) films as a tunneling harrier, we fabricated Au/Polyimide/1-layer arachidic acid/Pb structure in order to investigate electron transport properties through a junction. It was found that 9-layer polyimide LB films function as a good tunneling harrier in a study of current-voltage(I-V) chararteristics. And several peaks originating in the vibrational modes of the constituent molecules of 1-layer arachidic acid LB films were clearly observed in d<TEX>$^2$</TEX>V/dI<TEX>$^2$</TEX>- V corves.

水晶結晶微量天秤とＬａｎｇｍｕｉｒ‐Ｂｌｏｄｇｅｔｔ法により評価した油汚れに対する洗浄力（原標題は英語）

The titled assessment was conducted using a quartz crystal microbalance (QCM) and the Langmuir-Blodgett (LB) method. The gold electrodes of QCM were coated with cellulose acetate, nylon 6 or polyethylene film by spin-coating. Spreading monolayers of long-chain fatty acid as oily contaminants on water were transferred onto spin-coated polymer film. LB films of arachidic acid were ultrasonically cleaned in aqueous solution. Detergency was determined based on the frequency change of the QCM due to cleaning. Detergency was greatest for cellulose acetate, followed by nylon 6 and polyethylene. For all films, detergency increased with the addition of ethanol, surfactant and alkali. Detergency is discussed in relation to contact angle of aqueous solution on polymer film. Liquid introduction between LB film and the polymer surface in the zone of contact appeared to be a significant factor in the removal of LB film from the polymer surface.

Ferroelectricity of weak-polar organic molecules in alternate Langmuir-Blodgett multilayer films

Ferroelectricity in Langmuir-Blodgett (LB) films (Z-type and alternated Y-type) of nitrogencrown (NC) and arachidic acid (AA) was investigated by electric polarization measurements and surface pressure-molecular area π(π-A) isotherm. For Z-type AA LB multilayer and the AA LB films incorporating barium and manganese ions, as well as for Z-type NC LB multilayer and the Y-type NC/AA alternating LB films, typical hysteresis loops of the samples were observed and confirmed existence of the remnant polarizations in the LB films. Their corresponding remnant polarizations were found to be 15, 180, 650, 450 and 9400 μC · m−2, respectively. Therefore, it was demonstrated that the enhancement of ferroelectricity in the LB films could be created by incorporation of barium and manganese ions into the LB film structures and strong interaction between alternating monolayers of the samples. These novel approaches can be employed to create strong ferroelectric LB films to make ferroelectric thin-film device for practical applications.

Selective Langmuir–Blodgett Transfer on Phase-Separated Films

Abstract Mixed Langmuir–Blodgett (LB) films of arachidic acid (AA) and perfluorotetradecanoic acid (PA) took phase-separated structures with the monolayer domains of AA buried in the monolayer of PA. When two monolayers of AA were transferred on the 1/1 mixed LB films of AA and PA, AA was transferred only on the domains of AA in the mixed LB films.

Structural Changes in Mixed Langmuir−Blodgett Films upon Nanoparticle Formation

The formation of CdS nanoparticles by reacting mixed Langmuir-Blodgett films of arachidic acid and either octadecylamine or dimethyldioctadecylammonium nitrate on a cadmium-containing subphase with hydrogen sulfide gas has resulted in the identification of a number of structural changes, observed using grazing incidence X-ray diffraction. In the case of octadecylamine, the structure after reaction is a hexagonal close-packed array of surfactant-stabilized nanoclusters, with a lattice constant of a = 17.65 Angstrom. In both octadecylamine and dimethyldioctadecylammonium nitrate films, the presence of a unit cell tilted at 38degrees to the plane of the substrate was found. Despite these changes, the average nanoparticle size was unaffected by the addition of either second component to the film.

Detachment behavior of Langmuir–Blodgett films of arachidic acid from a gold surface studied by the quartz crystal microbalance method

The detachment process of an oily contaminant from a gold surface was investigated using a model system constructed by the application of the quartz crystal microbalance (QCM) method and the Langmuir–Blodgett (LB) technique. Long-chain fatty acid, arachidic acid, was used as a model oily contaminant. The solid-condensed monolayers of arachidic acid on water were transferred onto the QCM by the vertical dipping method. The frequency change of the QCM at each immersion–withdrawal cycle indicated that the monolayers were successfully deposited on the gold surface of the QCM as Y-type multilayers. The QCM having the LB films of arachidic acid was cleaned in aqueous solutions containing sodium chloride, sodium hydroxide, surfactants and/or ethanol by applying ultrasonic waves. Surfactants used were sodium dodecyl sulfate (SDS) and n-octyl β- d-glucopyranoside (OGP). The detachment efficiency of the LB films from the gold surface was evaluated from the frequency change of the QCM due to the detachment. The efficiency increased with time and showed saturation at 20–30 min. The detachment was found to increase with increasing concentrations of sodium hydroxide, SDS, OGP, and ethanol. At the critical micelle concentrations of SDS and OGP or at ca. 50 vol.% of ethanol, the LB films were perfectly removed from the gold surface. The detachment efficiencies obtained in all systems were correlated with the free energy change due to liquid penetration between the LB films and the gold surface, which was calculated from the experimentally determined contact angles and surface free energies. The saponification of arrachidic acid by alkali as well as the liquid penetration was found to contribute to the detachment of the LB films. The exposure of the 172 nm ultraviolet excimer light prior to the ultrasonic washing was effective for the removal of the LB films.

Structure of the Langmuir-Blodgett Films of Arachidic Acid Mixed with Amphiphilic Ammonium Ions and an Amphiphilic Amine

In the Langmuir-Blodgett (LB) films of arachidic acid (AA) with amphiphilic ammonium ions or an amphiphilic amine, components were mixed at the molecular level and formed salt. The alkyl chains of the two components took almost the same tilt angle. The fraction of the second component in the mixed LB films was smaller than that in the spreading solution when the fraction of the second component was larger than 0.5.

LB films formed from arachidic acid monolayers on an aqueous solution of a ruthenium(II) complex

Up to 91-layer arachidic acid (AA) LB (Langmuir–Blodgett) films containing photofunctional molecules, tris(1,10-phenanthroline) ruthenium(II) chloride hexahydrat (Ru(II)), were deposited by using Ru(II) aqueous solution as a subphase without any other ions. The AA LB films on Ru(II) subphase was characterized by the UV–visible, photo-induced emission spectra and low angle X-ray diffraction. Both absorption and fluorescence spectra have shown that the LB films have good optical properties in visible region. As many as five Bragg's diffraction peaks were observed in the 2 θ angle range of 1 to 10°, indicating that the LB films have good arrangement with the Ru(II) ions on the end of the AA chain homogeneously.

Salt Formation in the Langmuir-Blodgett Films of Arachidic Acid Mixed with Amphiphilic Ammonium Ions and an Amphiphilic Amine

Abstract In the Langmuir-Blodgett (LB) films of arachidic acid (AA) mixed with amphiphilic ammonium ions or an amphiphilic amine, AA was mixed with the second component at the molecular level and formed salt when the fraction of AA was not larger than 0.5. Further the fraction of the second component in the mixed LB films was smaller than that in the spreading solution with the fraction of the second component larger than 0.5.

Infrared studies of mixed Langmuir–Blodgett monolayers of octadecyldimethylamine oxide and dioctadecyldimethylammonium chloride with arachidic acid and poly(acrylic acid)

Infrared reflection–absorption spectra (IRAS) have been measured for monolayers of octadecyldimethylamine oxide (C 18DAO), dioctadecyldimethylammonium chloride (2C 18DAC) and their mixtures with arachidic acid and poly(acrylic acid) prepared by Langmuir–Blodgett (LB) technique on gold-evaporated glass slides. The spectra show that arachidic acid and C 18DAO or 2C 18DAC molecules form well-ordered monolayers with trans zigzag conformations. The order of the alkyl chain in C 18DAO is greatly increased upon the formation of the mixed LB film. The relative intensities of infrared bands due to CH 2 and CH 3 stretching modes of the hydrocarbon chains indicate that they are tilted with respect to the surface normal in the mixed LB films of arachidic acid and C 18DAO or 2C 18DAC. The hydrocarbon chains of C 18DAO and 2C 18DAC are disordered in the mixed LB films of poly(acrylic acid) and C 18DAO or 2C 18DAC.